Taimede valguskasutuse efektiivsus ning süsiniku ja lämmastiku bilanss: kaugseire kasutamine ja füsioloogilised determinandid

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Globaalsed kliimamuutused mõjutavad taimede kasvu, liigilist koosseisu ja tihedust ning seega ka toidutaimede ja puidu varusid. Oluliselt mõjutab inimesi ja looduskeskkonda ka ökosüsteemi võime siduda õhust süsinikku, kuna osaliselt inimtegevuse tulemusena atmosfääris kasvav süsinikdioksiidi hulk mõjutab samuti meie kliimat. Seetõttu uuritakse taimkatte süsinikuvarusid ja –voogusid järjest enam. Taimkatte omaduste globaalsete muutuste tõhusamaks hindamiseks kasutatakse kaugseire meetodit, mõõtes Maa kohalt taimkattelt peegelduvat valguskiirgust. Rahvusvaheliste projektide raames uuritigi, millised tegurid mõjutavad taimkatte süsiniku omastamist ja selle hindamist kaugseire meetodeil. Käesolev doktoritöö keskendub taimede valguskasutuse efektiivsuse uurimisele. Uuriti, kuidas reageerivad taimed valgustingimuste erinevustele ja kuidas taimede paigutus ning ehituslikud ja füsioloogilised erinevused mõjutavad lehtede ja taimede valguskasutuse mõõtmisi. Uurides erinevaid Euroopa puhmastikke, selgus, et niiskemas ja jahedamas kliimas võivad puhmastikud süsinikku neelata; kuivemad lõunapoolsed puhmastikud aga eraldavad süsinikku rohkem, kui fotosünteesi käigus omastatakse. Taimkatte omadusi (sh valguskasutuse efektiivsust) kajastavate peegeldumisindeksite kasutatavust taimkatte omaduste hindamisel mõjutas oluliselt puhmastike erinev struktuur. Samuti mõjutasid taimevõra ja lehtede struktuur ning füsioloogilised parameetrid lehe valguskasutuse mõõtmisi taimeliigiti erinevalt. Kõige enam reageeris valgustingimuste erinevustele lämmastiku jaotus taime erinevate osade vahel. Kokkuvõtvalt näitas käesolev uurimistöö, et taimede valguskasutuse efektiivsuse optilisel hindamisel tuleb arvesse võtta nii taimelehe, taime võra kui ka kogu taimkatte struktuuri ning liikidevahelisi valguskohanemise strateegiate erinevusi.Changes in global climate influence growth, species composition and density of plants and thus have a strong effect on global food and timber supplies. Additionally the ecosystem capacity to sequestrate carbon from the atmosphere influences our environment, since the partly human-induced rise in the carbon dioxide concentration of the atmosphere has a strong impact on global climate. Thus the investigations of plant carbon assimilation become more and more relevant. In order to increase the effectiveness of detecting changes in global vegetation, remote sensing methods, measuring optical reflectance of vegetation from space, are extensively used. During international projects the factors that influence the carbon budget of vegetation and the remote estimations of carbon production were investigated, while this thesis focused on differences in the light use efficiency of plants. The thesis investigated which parameters of plant structure and physiology are most responsive to changes in light environment, and how differences in those parameters affect optical estimations of light use efficiency of vegetation and single leaves. Research on different European shrublands revealed that moist northern shrublands may function as carbon sinks, while dry southern shrublands emit more carbon than is assimilated through photosynthesis. The remote estimations of vegetation parameters, such as light use efficiency, were strongly influenced by differences in vegetation structure. Leaf-level optical estimations of light use efficiency were affected by leaf and canopy structure and physiology as well, while the effect was dependent on plant species. Most responsive to differences in light conditions, appeared to be the distribution of nitrogen between different functional compartments of plants. In conclusion, this study revealed that if light use efficiency of leaves, plants or vegetation is estimated remotely using optical methods, leaf and canopy structure and species-specific differences in light-acclimation strategies must be considered

Morphology and structure of putative fossilized phosphatic sulgur-bacteria and methanotrophic archea in 2.0 Ga old organic-rich mudstones, Zaonega formation

http://tartu.ester.ee/record=b2653466~S1*es

VICARIUS, CANONICUS ET EPISCOPUS : THREE LATE MEDIEVAL GRAVE SLABS FROM TARTU AND TALLINN

The article discusses three late medieval grave slabs in Estonia, which are decorated with full fgures and represent ecclesiastics of diferent ranks. By examining their visual appearance, including the inscriptions and coats of arms, some of the general trends in the production and decoration of local tombstones can be outlined and a contribution made to the discussion of the role of such monuments in the late medieval culture of commemoration. One of the slabs, actually a fragment, came to light during the archaeological excavations of the Tartu Cathedral in 2008. Its inscription added a completely new name to the list of clerics known from medieval Tartu. The monument belonged to the vicar Stephanus de Velde, who died in 1428 or 1438. The others two grave slabs are located in the Cathedral of Tallinn. One of them, belonging to an unidentifed bishop, can be dated to the frst third of the 16  century. The other marks the grave of Georgius (Jurgen) Bardin, a canon in the Tallinn and Saare- Lääne (Ösel-Wiek) dioceses, who died in May 1525. An important function of these monuments was to be a witness to status. The identity of the deceased was perpetuated through the proper attire and symbols, but also through the family coat of arms and the name and occupation stated in the inscription. The large and elaborately decorated grave slabs were prestigious objects, which were meant not only to mark the tomb but also to visually commemorate the deceased, to invite the viewers to contemplate on death, salvation and resurrec- tion, and to evoke intercessory prayers

Effect of Gliocladium catenulatum J1446 to the respiration rate of the bumble bee Bombus terrestris

The effect of Gliocladium catenulatum J1446 to the respiration rate of the bumble bee Bombus terrestris was investigated

Using honey bees to disseminate the biocontrol agent Gliocladium catenulatum J1446 to strawberries for Botrytis cinerea control

Using honey bees to disseminate the biocontrol agent Gliocladium catenulatum J1446 to strawberries for Botrytis cinerea control was investigated in this study

Meemesilase ja biofungitsiidi Prestop Mix kasutamine aedmaasika hahkhallituse tõrjes

The study was conducted in 2010 in five experimental areas of Tartu County. Honey bee hives were placed at the edge of strawberry fields at first bloom; each hive had a special dispenser attached containing the biofungicide Prestop Mix, which is a preparation of the parasitic fungus Gliocladium catenulatum. As the bees exited the hive through the dispenser, they were dusted with the Prestop Mix preparation and carried it to the strawberry field. Two treatments were established: 1) a bee-excluded untreated check (covered with exclusion cages), and 2) a bee-delivered Prestop Mix treatment. We compared the bee-disseminated treatment with the untreated check by counting the healthy and Botrytis-infected berries; we also compared strawberry varieties. Our results show that treating the strawberry plants with the bee-dispersed Prestop Mix reduced the proportion of infected berries over 10% compared to the check. We also found that the efficiency of the treatment depended somewhat on the strawberry variety: the variety ‘Sonata’ compared to ‘Polka’ was slightly more efficient